Multi band antennas are antennas providing wireless signals in multiple radio frequency bands, i.e. two or more bands. They are commonly used and are well known in wireless communication systems, such as GSM, GPRS, EDGE, UMTS, LTE, and WiMax systems.
This type of multi band antenna often comprises a reflector structure for controlling the radiation of the antenna, e.g. beam width and lobe pattern. To achieve this end, mentioned types of reflectors may have different shapes and setups depending on the frequency in use and the desired radiation pattern, etc.
FIG. 1 schematically shows, in cross section, an example of a reflector for a triple band base station antenna according to prior art. The reflector is placed behind one or more radiating antenna elements in use and is arranged to provide, together with the radiating elements, desired antenna radiation characteristics.
However, it has proved difficult to provide reflectors having reflector structures suitable for multiple antenna frequency bands giving desired antenna radiation characteristics. This is especially the case for multi band antennas arranged to transmit in three or more frequency bands.